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Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide (2009)

Chapter: Chapter 3 - Enabling Shared-Track: Technology, Command, and Control

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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Suggested Citation:"Chapter 3 - Enabling Shared-Track: Technology, Command, and Control." National Academies of Sciences, Engineering, and Medicine. 2009. Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner's Guide. Washington, DC: The National Academies Press. doi: 10.17226/14220.
×
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Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Introduction The technology essential to enable shared track operations encompasses Command and Con- trol systems, signal and train control, communications, and vehicle technology. The choices are influenced by economic and regulatory considerations. Technology options impact the business and safety cases. This section reviews the variety of train control systems, communications systems, operational Rules and Procedures, and vehicles that are particularly suitable or adaptable to the shared-track environment. The emphasis is on those features or characteristics that will compensate for vehi- cle structural deficiencies by minimizing the risk of a collision or mitigating the effects in such an integrated system. Above all, this combination of features and capabilities will have to fulfill the FRA safety mandates. Achievement of those objectives does not imply that all systems and vehicles should be FRA- compliant. Rather, they must satisfy Federal guidelines and conform to jurisdictions and princi- ples established in the 1999 joint FRA/FTA policy statement, which were subsequently codified in current regulations, 49 CFR Parts 209 Appendix A and 211 Appendix A. Under these require- ments, the FRA must be satisfied that all technical and operational aspects of the proposed shared- track system are sufficiently safe prior to authorizing revenue service. A survey of operational and proposed systems, summarized in Chapter 4 (performed for the Task 5 Report), strongly suggests that a fail-safe train separation system and intrusion detection in high risk areas are critical, and a necessary prerequisite to concurrent shared-track operations. The importance of autonomous collision prevention is amplified when the vehicles involved have disparate structural capabilities, speeds, or weights. The Role of Command and Control Systems in Shared-Track The growth of shared-track applications in the United States is dependent upon the evolution of fail-safe Command and Control systems that provide no ambiguity, overlaps or gaps in author- ity, misunderstanding or disagreements among users. It is important that the research establishes minimum requirements of Command and Control systems for shared-track operations and rec- ommends potential enhancements to assure the safety of all users. Command and Control can be seen as a triangular relationship of elements that, when prop- erly integrated, improves safety and supports operational requirements and passenger and freight service objectives. The elements are: 27 C H A P T E R 3 Enabling Shared-Track: Technology, Command, and Control

1. Train control systems; 2. Communications technology; and 3. Rules and procedures. Effective integration means that Rules and Procedures are woven into the train control system, in conjunction with a communications network, to assert effective C&C over all train movements while protecting employees and the public. Together they provide redundant fail-safe features to prevent collisions and protect against technical failures or human errors. Each individual facet contributes in a complementary manner with the other two. If one com- ponent of the triangle malfunctions, the remaining two elements must compensate for the defi- ciency. During such eventualities, performance can be permitted to suffer, but safety cannot be compromised, particularly in a shared-track environment. Rules and procedures take on greater importance under such circumstances. Train Control Technology Signal and train control technologies are defined as those technologies directly involved in ensuring the safe movement of trains and preventing collisions. This segment reviews current and emerging train control technologies that can provide fail-safe backup to override inevitable human errors and therefore assist in preventing collisions between trains on the same tracks, and between trains and other encroachments into the clearance envelope of an adjacent train. The applicability and practicality of train control technologies for a shared-track setting are assessed and evaluated. Evolution of train control systems has been propelled by many factors. Accident experience and a desire to avoid financial losses, injuries or fatalities, ultimately have driven technological innovation and influences principles of design. More recently, regulations have assumed a greater role in forcing technology development and deployment. Finally, any system must be proven to serve its intended purpose and satisfy functional requirements. Practically speaking, multiple stakeholders must be satisfied with the design, manufacture, installation, and testing of a train control system. While such issues are generic to any train control systems design, their implemen- tation in a shared-track environment merits special attention. In FRA and railroad parlance, they are considered vital systems. 1) Train Control System Functions Train control systems are designed to prevent three major types of collisions: (1) head-on col- lisions between trains traveling in opposite directions on the same track; (2) flanking collisions for trains moving or standing on a siding when approaching or departing a main line track; and (3) rear-end collisions between trains following one another. However, train separation alone does not mitigate all hazards. Besides train-train collisions, a shared-track system poses some unique risks. Intrusion collisions, where freight equipment intrudes on the active passenger track due to a roll-out, derailment, or shifted-load, are not necessarily detected by the train control system. Secondary collisions between freight and pas- senger equipment (i.e., caused by an intrusion event) may not be prevented by the train con- trol system, so the best course is to prevent the primary (root cause) event. Where track is shared between compliant and light passenger rail cars, the FRA has required fail-safe train separation as a sine qua non for its approval. Figure 1 outlines technological approaches to train control that regulators would find acceptable without excessive scrutiny or burdensome strictures. 28 Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner’s Guide

Enabling Shared-Track: Technology, Command, and Control 29 Train control technologies for railroad and transit operations are mature, but continue to evolve with the introduction of improved technology and components that offer additional capabilities. Train control systems are first and foremost installed to ensure safety. They provide three basic protective functions: 1. Train detection—indicates presence and location of trains; 2. Train separation—maintains safe following distances between trains; and 3. Route interlocking—prevents unsafe moves on/off branches or conflicting routes through crossovers and turnouts (that might cause collision or derailment). Conventional signal systems are required by federal regulations where passenger train speeds exceed 60 mph, although shared-track would merit a signal system at any speed. Above 80 mph, federal regulations generally require active protection against three situations regardless of oper- ator performance: (1) entrance to occupied block; (2) overspeed with respect to signal aspect; and (3) operator error. The most significant limitation for shared-track applications of conventional fixed block is that multi-aspect signal technology, typically sufficient for passenger operations (below 80 MPH), is not adequate for shared-track operations, due to its lack of active protection. Wayside signals relay information with the expectation that the operator will respond properly. Override capa- bilities are not provided to catch and correct operator error. Consequently such conventional signal systems are not likely to be deemed acceptable for a shared-track environment with light passenger rail cars, regardless of speed. 2) Train Control System Design Parameters The design of signal systems must be based on assumptions and parameters that include max- imum speed, train acceleration and deceleration rates, train length, route gradient, curves, and civil speed limits. Other factors, such as number of tracks and features like reverse running, also are considered. Designers usually apply various safety factors (for example, diminished braking performance and additional stop distance margins) to system criteria to allow for potential fail- ures or malfunctions of the vehicle. As shared-track operations are planned, the signal system must accommodate both short light rail cars and longer freight trains, with widely different stop- ping distances. Adjustments to basic designs are made to take into account system service objectives, protection features, overspeed conditions, wheelslip/slide conditions, brake system failures or deficiencies, gradient, curvature, visibility, civil speed limits, rail volumes and variety of traffic, and other Head to Head Flanking Rear-End A B A B AB Example scenarios: Train A is routed into siding Train B runs stop signal Train A has a straight ahead move Train B runs stop signal Train A is delayed Train B runs stop signal Figure 1. Train accident scenarios.

relevant factors. All designs must consider failure scenarios involving train control technology, rail vehicle functions, and human factors. Most freight branch lines are dark (unsignaled), and therefore lack basic train protection capabilities. With low traffic levels operating at low speeds, train control mechanisms are sim- ple and inexpensive to maintain. If any passenger service is contemplated on such a route, addi- tional features need to be incorporated to provide better train protection, more operational safety, and flexibility. Certain features are mandated by regulation, whereas others simply improve the service or line-haul capacity. Although a passive system (dependent on the human operator) may be acceptable, an active system (that compensates for human error or component failure) is preferred. The addition of a train control system can be viewed as a no cost fringe benefit from the freight operator’s perspective. Whatever the design requirements or features incorporated in a basic train control system, there are fundamental regulatory requirements for any train control system design: • Prevent entry into an occupied block; • Stop distance to signals must be based on full-service brake rate; • Provide broken rail protection; and • Invoke automatic train stop systems based on maximum authorized line speed. Each impacts the train control system design for shared-track operations. 3) Train Control Technology—Conventional Systems Conventional or traditional train control technology is based on fixed blocks, multiple aspect, power frequency or direct-current (DC) track circuits. The fundamental element of a basic train control system is the block. The block is a section of track with defined limits. Its occupancy is governed by a signal. Figure 2 shows a simple example. Each vertical tic mark indicates a separate block. Block lengths are established during signal design. Each block is an electrically separate track circuit, and individual lengths vary. Train movement is controlled by signals that require an appropriate response by the train operator. Train control technology now in service in the United States is mature, reliable, well under- stood and based on simple, time-tested principles. In fact, this advanced stage of development obstructs the introduction of new technology or its adaptation to nonconventional applications. 4) Train Control—Emerging Technology—PTC and CBTC Positive Train Control (PTC) and Communications Based Train Control (CBTC)were devel- oped to expand the train control and information services provided by the signaling system. PTC refers to a North American family of train control technologies that provides functionalities over and above the most advanced continuous cab signal systems. PTC and CBTC are being devel- oped for high-density or high-speed lines such as urban heavy rail rapid transit lines and mixed passenger/freight main line applications. However, they are not necessary for fail-safe train sep- aration required for concurrent operation of conventional railway rolling stock and light pas- senger rail cars on shared track. 30 Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner’s Guide Figure 2. Signal block layout.

5) Train Control Technology—The Supply Side The process of creating a practical train control system is lengthy and expensive. Designs must be prepared, products manufactured, components assembled and installed in the field, and the system tested. Since the dominant issues include products and installation, the supply side is often the most significant of all to stakeholders. The signal supply industry falls into three major categories: • Large, full-service suppliers; • Niche or specialty product vendors; and • Procurement consultants. System suppliers and consultants assume primary responsibility for transforming operat- ing requirements, standards, regulations, and design parameters into a functioning train con- trol system. The supplier is responsible for the most important phases of implementation: manufacture of hardware, assembly of components, and system testing. Once installed, sig- nal systems tend to have a long life cycle, and can serve reliably for more than 30 years with periodic maintenance and repairs. A long-term business relationship is the norm between the operator and the vendor, as specialized or proprietary parts often are necessary for repair and maintenance. This association is compounded by the vested expertise effect: when agency staff becomes accustomed to a particular product line, familiarity and experience often result in a sole-vendor relationship. 6) Proving the Train Control System Basic Testing Requirements New signal system installations must be proved in a succession of steps. The system is first cut-in by joining hard wire connections from rails to vital equipment in bungalows. Func- tionality is verified through a series of local and component tests. The tests are then gradually extended and combined to include adjacent interlockings. Once signal engineers are satisfied that the system is safe, test trains are run to confirm performance. There is nothing particu- larly novel about this sequence. The FRA establishes test requirements for signal system com- ponents and functions. • 49 CFR Part 234.247 to 234.273 specifies Inspections and Tests for Grade Crossing Equipment. • 49 CFR Part 236 specifies Inspections and Tests for various categories of equipment includ- ing Systems, Interlockings, Traffic Control Systems, and Automatic Train Stop and Cab Signals. While these requirements are geared towards regular maintenance and inspections, they are also the starting point for a new installation. Often a railroad will create a more detailed inspection and test plan tailored to its own installation. System and Integration Testing—Vendor Role Vendors also must test and prove other aspects of new train control systems, to verify per- formance and functionality. Such tests are witnessed or monitored by the operator, to authen- ticate the test performance and results. In a shared-track operation, such testing will be required with conventional rolling stock and the light passenger rail car. By this point all assemblies, components and equipment would have passed factory tests. Once in place on the railroad, there is typically a six-step field and wayside test and inspection program: (1) installation test- ing; (2) static testing; (3) integration testing; (4) dynamic testing; (5) design or field changes; and (6) retest. Enabling Shared-Track: Technology, Command, and Control 31

Proving the system also may include other activities such as: • Test plans, procedures, and reports—normally defined in procurement documents; • Maintenance—inspections and periodic testing—addressed in 49 CFR Part 234 and 236 tests; and • Verification and validation—typically required for software based systems. 7) Practical Considerations for Shared-Track Because of its impact on safety, train performance, and operator behavior, the selection of a train control system may be the most significant choice for a transit agency considering shared- track. Transit-like (2–5 minutes) headway is not envisioned on shared-track lines. Most likely, an occasional freight move is required along the corridor during an off-peak period when the transit vehicles are running at 20–30 minute intervals. In some cases, the last few passenger trains of the day would overlap with a freight train switching on-line industries. Train control can be the dominant influence on the regulatory review process and directly affect the viability of the project. The choice of technology is influenced by many considerations. Some of the most important are: • Current train control technology is mature and offers little room for improvement. Marginal improvements are achieved at significant cost. Absent a strong business case, there is little incentive to change or upgrade the technology. • Design, manufacture, and installation of train control systems are expensive and require a long lead time. Once in place, train control systems are not readily adaptable to changes in tech- nology or operating patterns without incurring substantial costs and time-consuming field modifications. • Railroads and regulators can be very conservative in adopting new technologies, particularly where safety is affected. The FRA staff carefully scrutinizes any divergence from requirements of 49 CFR Parts 234 or 236. While deviation from regulations is sometimes incorporated, each must be justified to the FRA case by case. • The system must be suitable for both freight and passenger equipment. It also must fulfill owner specified requirements and support the service plan envisioned. 8) Issues Unique to Train Control for Shared-Track When choosing a train control system, the prospective operator is advised to develop a design that meets FRA regulations and acknowledges the need to submit a waiver petition to the FRA. The system designers and operators should engage the Federal authorities as early as possible to engineer an acceptable train control system. Any request for relief from Federal requirements must be justified. The following technical choices may encourage a favorable regulatory review and acceptance by the freight operator. 1. A train control system that provides fail-safe train separation is essential for concurrent operations. 2. The train control system should favor the transit operation and accommodate only an occa- sional freight movement among off-peak passenger service. 3. The design should consider the needs of the freight operator in addition to standard passen- ger rail service requirements. To enlist cooperation of the freight operator, the benefit of a new train control system should be quantified. 4. Designers should consider vehicle shunting characteristics for both conventional and light rolling stock, for track circuits, and grade crossing warning systems. 32 Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner’s Guide

5. System designers should incorporate a complementary approach to the human interface of the train control system, including: (a) a full function control-center; and (b) appropriate operating Rules and Procedures. 6. The system must accommodate a transition between line-of-sight street running (if the sys- tem has a street running portion) and cab signaled territory. Light passenger rail cars must not enter shared territory without functioning cab signals without a safe operating protocol; con- ventional equipment must be prevented from entering street running sections by accident. The objective is to use signal technology to prevent collision hazards by enforcing movement authority. No new technology is necessary, but the train control system must provide the mini- mum required feature set defined here, including the fail-safe train separation requirement and an emphasis on local hazard mitigation technology using auxiliary safety critical systems. All com- ponents are readily available in off-the-shelf configurations from multiple full service and spe- cialty vendors. However, application of current technology to novel situations may be required. Auxiliary Safety Critical Systems Safety concerns for track sharing are compounded due to structural disparity between con- ventional equipment and light passenger rail cars. Four issues are especially prominent shared- track concerns. 1. Intrusion Detection. Advance warning of encroachments on the light rail train clearance envelope. Two types exist, continuous and point detection. One such device is illustrated in Figure 3: 2. Hazard Detection. Prevention or warning of failures in freight equipment or other hazardous conditions that could result in derailment, such as rock slides, hot axle boxes, or dragging equipment. Detection devices may be necessary where freight is operating nearby, preferably close to limits of shared-track zones. 3. Roll-out Prevention. Prevention of freight equipment roll-outs from sidings or at crossings, onto the main line used by a light rail train. Typically derails and electric locks are used for this protection. 4. Broken Rail Detection. Detection of rail failures, potentially averting derailments. This func- tion is typically provided by a track circuit. Placement of these systems should consider volume and speed of the freight traffic, train length, type of cargo, terrain, gradient, track centers and visibility. If feasible, fixed barriers and Enabling Shared-Track: Technology, Command, and Control 33 Alarm Point Laser Scanner Laser Field (approx. 3 inch wide) Figure 3. Intrusion detection technology.

other methods of limiting potential damage from a derailment should be considered. Detectors generally don’t prevent problems, but provide early warning of hazardous conditions, and can be more easily installed. When a detector is triggered, an interface with the train control system normally causes nearby signals to display a STOP aspect and also broadcast a radio alert to oper- ators and the control center. Generally the operating rules stipulate that all traffic must halt until a restart movement command is received from the control center. The control center would investigate the cause of the alarm and confirm a safe condition exists before authorizing traffic to resume. Interoperability of Freight Trains in Shared Territory A key issue for shared-track operations is the compatibility of freight equipment with the train control system. The locomotives used on branch lines can be a dedicated fleet, and fitted with the vehicle-borne cab signal apparatus. They will operate normally in a cotemporaneous man- ner, with the train control system ensuring safe spatial separation between trains. The controls on board a locomotive would be programmed differently to factor in freight braking rates and operating speeds. Freight train lengths may exceed the length of light passenger rail trains. A longer freight train could occupy two or more track blocks. The train control system should automatically accommodate the longer train. The most difficult condition is the operation of a nonequipped “foreign” (i.e., from a railroad outside the shared-track corridor) locomotive on the shared-territory. Where unequipped freight equipment operates, special operating Rules and Procedures will assure operating safety. • Temporal separation methods can be used to backstop the occasional situations where non- equipped conventional equipment must detour over the shared territory. • If conventional trains only travel for a short distance on shared-track, turnouts can be set and locked to give the nonequipped freight train exclusive possession while they make the move- ment. The train control system will still prevent intrusions by passenger trains. Application of speed control systems to freight trains is potentially problematic. Enforced braking of freight trains has two principal drawbacks. 1. The braking performance of a freight train is more variable and unpredictable, depending on the mix of loaded and empty cars, the car types in the train, and the condition of the brakes. 2. Too high a braking rate can result in high longitudinal forces in the train, potentially leading to damage and derailment. However, with a properly designed enforcement system, freight locomotives could apply a low braking rate that does not pose a derailment risk. This is feasible and may be justified for a captive fleet of locomotives where freight trains travel for a substantial distance on the shared-track. Planners are advised to review typical freight cargo, train lengths, operating speeds, active tracks, car counts, and other traffic characteristics along with track alignment and geometry. This can aid in identifying potential hazards or warning system locations. 9) Fail-Safe Train Separation If a true cotemporaneous operation is planned, a higher level of safety assurance is required. The train control system must prevent a human error or component failure from jeopardizing operational safety. A minimum off-the-shelf shared-track train control system should feature intermittent or continuous cab signaling. The recommended system uses appropriate combina- 34 Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner’s Guide

tions of traditional signaling technology. The system should incorporate automatic train stop capability and overspeed protection. • Automatic train stop capability: vehicle-mounted components that communicate with the signal system to force a train stop when there is insufficient separation from the train or obstruction ahead. The primary additional device is a receiver to read and process informa- tion carried by track circuits, beacons, or electro-magnets. The carborne receiver is specific to the chosen train control system. • Overspeed protection: limit train speed to below posted speed limits to prevent excessive speeds on curves or through switches and to provide adequate stopping distance. In general, these methods of providing fail-safe train separation supply additional function- ality using elements physically integral to the rest of the basic train control system (track circuits, line wires, and bungalows and wayside signals) and adding appropriate components. Essentially, the train control system monitors train speeds where speed reduction is necessary. The location to begin braking is selected on the basis of entry speed, deceleration rate, and dis- tance to go before encountering a stop signal or a collision hazard. a) Applications of Automatic Train Stop Systems (ATS) (Intermittent) Basic railroad-style ATS systems are unlikely to provide an adequate level of collision safety, especially on single-track lines. The high number of train meets at passing sidings, and the chance of an “acknowledge and forget” event constitutes unacceptable risk. Transit-style ATS, with an enforced stop on passing a signal at danger combined with modest top speeds and high braking rates is an option for less demanding applications. Transit ATS could be applied where freight traffic is very low or where passenger vehicles are to be prevented from encroach- ing on a short section of track “locked out” temporarily for a freight movement, as on NJ Transit’s Newark City Subway. Enhanced ATS appears to be the most attractive for concurrent shared-track operations. The risk of “acknowledge and forget” incidents is much reduced by the additional warnings and enforcement to limit speed approaching a danger signal, and by enforced braking on passing the danger signal. b) Applications of Cab Signal Systems (Continuous) Traditional power frequency fixed block systems with cab signaling and enforcement, like that installed on the Northeast Corridor and on New York area commuter rail systems, is mature and also would be suitable. Designed for high density, high speed operation with mixed locomotive-hauled and multiple-unit trains, they will likely exceed safety require- ments for ordinary shared track operations. c) Audio Frequency Coded Track Circuits: The State of the Art Continuous cab signal technology (in “b” above) requires high capital and maintenance costs. Recent technological advances have reduced somewhat the life-cycle costs of coded-track cir- cuit based systems. Compared to a traditional cab signal system, the audio-frequency track circuit system has many advantages. • Lower capital and maintenance costs – Testing and maintenance burden is minimized – Fewer relays are used, thus bungalows and relay cases are smaller – Fewer impedance bonds – Fewer conductors means fewer terminations and less wire tagging, simpler installation – Very few insulated joints, reduces installation and track maintenance costs • Easier to bid and award because of nature of technology and larger pool of vendors • Track circuit lengths are easier to tailor to a route – Longer in line-haul segments – Shorter near stations and crossings, for better operational control Enabling Shared-Track: Technology, Command, and Control 35

The audio frequency track-circuits provide both train detection and transmission signal aspects. The vehicle borne equipment reads the code and interacts with the train control system to alert the operator and/or reduce train speed as necessary. There is ample domestic light rail experience, and the system can be designed to comply with federal regulations. The cost is likely lower than power frequency cab signal systems, but thus far has not been applied in the U.S. mainline rail- road environment. Table 5 provides an overview of the capability of train control systems in hierarchical order, lists primary components, and notes the extent of safety hazard protection each affords. Appendix 4 provides relative cost comparisons of various train control systems for planning purposes. Command and Control: Communications 1) Communications—Information Processing Railroad communication systems allow operating personnel to capture operational and other essential status information; transmit it to various locations, devices or persons that require this information; enable the systems to process or users to view the various condi- tions; and issue commands to control, alter or otherwise acknowledge the status. The con- stituent pieces that effect this capture and transmission of information and serve both verbal and data content include: • Command & control information—voice, data (i.e., the information content to be monitored or transmitted); • Carrier technology—medium of transmission via wire, wireless radio, fiber optic, land line or cell phone; • Carrier frequency—VHF, UHF, SHF, spread spectrum (i.e., the format of the data transmitted); • Communication system components—hard wired or portable radio, landline or cell phone, CRT display, mimic board, data transmitters/receivers, compatibly linked via interface devices to the transmission and frequency carriers. 2) Regulatory and Practical Requirements For shared-track operations, an entirely new communications system will be required for the passenger service, and must, by regulation, incorporate direct interconnection with the freight carrier. On a shared-track system, the transit control center should be the exclusive hub for all freight and transit communications related to safety and train movement. The system component design and functionality must be based on a combination of published standards and regulations. • Onboard equipment has to comply with the APTA Manual of Standards and Recommended Practices, for Rail Passenger Equipment, Volume VI, Standard for Passenger Railroad Emergency Communications and American Railway Engineering and Maintenance of Way Association (AREMA) Communications & Signal Manual of Recommended Practices Volume V, 2006. This contains railroad frequency and channel information for radio transmission systems. • FCC requirements. Operator needs to apply for license for base stations (antenna height, broadcast range, and frequency license for transmission) for all wireless communications networks. • FRA requirements. Operator must comply with relevant FRA regulations for railroad com- munication. The FRA regulations and policies for shared-track operations appear in the Code of Federal Regulations (CFR), in 49 CFR Parts 209 and 211. Other Federal Regulations includ- ing 49 CFR Parts 217, 218, and 220 also influence the control of rail operations. Requirements 36 Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner’s Guide

Table 5. Overviews of capacity of train control systems. 37

and constraints noted within these regulations should be evaluated for their applicability to shared use. All railroad communications are subject to FRA Part 220, which mandates radio requirements, wireless communications procedures, and what to do in the event of commu- nications failure. . . . any train that transports passengers shall be equipped with a working radio in the occupied controlling locomotive and with redundant working wireless communications capability. . . . • Safe and effective Command and Control requires that the communications network and transmission must limit access for safety and security purposes. Technology allows for a controlled flow of information between two or more key participants outwards to multiple subscribers through a central hub or between central hubs such as control centers of freight and passenger railroads. 3) Purpose of a Communications System One of the most important uses of communication is to back up or provide an alternate or supplemental means of train control in the event of failure or service disruptions. Whatever the technology, verbal communication remains the foundation of safe and efficient movement of trains. In the context of this report, verbal communications refers to communication either between a control center and/or supervisory personnel and the train operator or other staff. These requirements extend to work equipment on the right-of-way (ROW), MOW crews, or lone workers under specified circumstances. The focus here is on non-vital systems and methods for information transmission (data or verbal), the content of that information, and the resulting action. The human interface for send- ing, receiving or responding to that information merits consideration in the practical outcome of the transmission. 4) Functional Design of a Communications System In conventional railroad parlance, communications is considered non-vital but nevertheless essential. The communications system is supplemental to the train control system, augments it, and provides redundancy. This non-vital information is monitored and captured. Communica- tions data flows through four steps. A. Capture Information: Monitor, report status, conditions or events, digitally or verbally. The system operator may wish to capture certain types of data and will provide sensors or read- outs such as: • Vehicle identification, location (direction and speed), condition; • Signal status (display and health); • Grade crossing warning system status; • HAZMAT (hazardous materials shipment) information; • Track clearance intrusion; and • Hazardous event detectors (dragging equipment detector, hot box). B. Transmission via the Communications Backbone: Conveying information verbally or digi- tally from the capture device to the display device, using the communications backbone, either wired (including fiber optic and copper), or wireless. C. Display Information: Receive information and present or report it in an actionable format. Vehicles, control centers, and other monitoring devices and systems are typically equipped with status information displays and alarm/alerting systems. The status display simply pro- vides current information about a given device, or function. 38 Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner’s Guide

D. User Interface: A user initiates a control action or responds to the captured information via an interface device (e.g., a control panel). Most displays involve a graphic user interface (GUI) and include alarms (continuous or one time). GUI can be a touch screen, keyboard, or mouse. Typically all information displayed and responses are recorded on a data base for retrieval, should it be necessary. Generally two independent data storage and retrieval sys- tems are provided for redundancy, as are multiple monitors. 5) Communications Systems for Shared-Track A single communications center as a hub for Command and Control is essential for the shared-track operation. Given the fundamentals of the railroad communications system, what guidelines should influence the choices for a shared-track operation? The operator should weigh the factors that affect technical selections, such as capital costs, maintenance costs, personnel skills, proprietary systems, expandability for growth, and adapt- ability to technical progress, as well as reliability, redundancy, practical user friendliness, band width, and frequencies. Some benefits or capabilities are considerably more appealing to passenger operations, and safety issues loom larger where passengers are involved. Clearly any shared-track operations will require a working radio on trains and work equipment, for designated personnel, and a redun- dant capability. Communications with passengers and with a Control Center are not new to rail transit systems. Coordinating transit operations with a freight carrier and developing and using joint communications protocols will be new. A unique design or advanced technology is not required for shared-track. Conventional systems properly applied are sufficient. Command and Control Systems: Rules and Procedures 1) Purpose Rules and Procedures (R&P) were created to manage the operation of railroads and transit systems. They are published in a rulebook and other ancillary documents, and issued to desig- nated employees. Most follow a standard format and topical coverage, although they are tailored to the individual line or system. Passenger and freight R&P are different. Whatever the choice of train control, communications technologies, and capabilities, integration with R&P completes the framework of C&C. First and foremost R&P are about safety. The significance of human factors in accidents is not lost on the railroad and transit sectors. Thus, R&P remain fundamental to all passenger and freight operations. They: • Provide needed redundancy in the event of equipment failures; • Complement and compensate for the limitations of technology; and • Provide a prioritized set of operating protocols critical to assuring the safety of shared-track operations, but are not entirely dependent upon train control technology. 2) Regulatory Mandates The crucial importance of operating R&P in shared-track operations is recognized by the FRA in 49 CFR Part 211, which details the FRA policy with respect to shared-track. Directly applica- ble to Command and Control systems, the FRA specifically requires the freight and passenger operations to be capable of communicating directly and adhering to common operating rules where track is shared. Other relevant regulations include 49 CFR Part 214 Railroad Workplace Enabling Shared-Track: Technology, Command, and Control 39

Safety, Part 217 Railroad Operating Rules, Part 218 Railroad Operating Practices, Part 225 Rail- road Accident and Incident Reporting. 3) Rules and Procedures—Practical Considerations Both freight and passenger operator must be under the authority of the same control center, preferably managed by the passenger operator. The control center must be able to communicate with train crews, MOW crews, supervisors, and maintenance of equipment (MOE) personnel and vice versa. In the case of shared-track operations, freight crews and other personnel must be able to communicate with the passenger control center and be trained and conversant in their R&P. In a shared-track environment, the day-to-day operation encompasses the four likely scenarios over a typical service day or during special operations. A. Shared-track operation of light passenger rail cars movements commingled on the same track where freight movements occur; B. Parallel movements involving light passenger rail cars on one track and a freight train on an adjacent track; C. Exclusive use by either the light passenger rail cars or the freight equipment; D. Transitional periods when passenger service is starting or ending, in conjunction with freight period ending or starting. Different rules and procedures for freight and passenger operations when combined for freight and passenger traffic in a commingled operation must accommodate those four scenarios as well as some unique to each mode: • Freight operations. Train control system, communication protocols, speed, train length, cargo, drill operations, train inspections, shifted loads, fouling of main tracks, close clearances, and accident/incident response; and • Passenger operations. Train control system, communication protocols, pre-departure safety inspections, schedule, speed, changing ends, terminal activities, passenger conduct and rela- tions, station stopping, movements at grade crossings, hazardous condition alerts and accident/ incident response. In most cases rule books are issued to employees, who receive training, and then are responsi- ble to learn the rules, keep up-to-date with changes, and have the books on or near their person at all times while working. To contribute to safety, R&P also serve these purposes. • Governance: Specify the duties of operating and maintenance employees and direct their actions in any situation that may arise while they are operating trains or controlling or affected by train movements. • Regulatory conformance: Fulfill regulatory requirements. • Acknowledge limitations: Recognize the limitations of technology and human capabilities and behavior, and compensate for these shortcomings. • Supplement train control systems: They are designed to address circumstances not accommo- dated in the train control system and failures of technology, and to provide safe work arounds for most eventualities. 4) The Rulebook The ideal system of R&P will provide movement authority for all foreseeable situations. Rail- road-based rules and procedures are preferred as the nucleus, for a rulebook that provides: • Sufficient and appropriate content for the nature of the operation; • Adequate management resources to staff, train, and monitor application and enforcement of R&P; 40 Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner’s Guide

• Proficiency testing, fitness for duty and fatigue management practices; • Supplemental and revised documents to reflect system or operational changes; • Physical characteristics map and guide of the route for each employee; • Communications protocols for all employees of the passenger and freight system. A reliable communications system that links the control center to light passenger rail cars, freight equipment, MOW crews and work equipment, MOE crews and supervisors, and monitors/ commands the train control system. • Guidelines and instructions for incident and accident response and management While each system’s rulebook may be organized differently, they all cover similar themes in a way appropriate to their system and culture. It is important that the freight operator be involved in the process of drafting the rulebook. While not all topics will be of concern to the freight carrier (e.g., light rail transit street running), there must be concurrence on topics of mutual interest. 5) Rules and Procedures for Shared-Track Operating R&P defines how the signal system directs train movements and interactions between traincrews, the control center, and trains. Rules describe signal aspects, their meaning, and standard procedures both in normal operation, and when failure occurs. This is a key aspect of train control and must complement the characteristics of the operation and technology. Shared-track operation complicates the development of rules because operating procedures for freight trains will necessarily differ from those for light passenger rail cars. Designers of a shared- track operation should address some or all of the issues bulleted below. • A prospective operator for shared-track operations should be cognizant of the mandates of FRA/FTA policy and regulations. • The agency operator must blend cultures and practices developed to serve freight movements, passenger operations, and a street running light rail transit (LRT) operation. • Implement joint training and testing programs, common rulebooks, user based special instructions and procedures, and physical characteristics training, including periodic revisions and currency updates. Institute proficiency testing. • Delineate ownership and responsibilities of each entity using the corridor, creating a need for communication between the parties at both a senior management level and the front line level for day-to-day operations. • Understand that Command and Control practices that may be necessary or appropriate for a passenger operation may not be valued, or may be perceived as impediments to their opera- tions, by the freight carrier. • Establish a control center that can set signals and switches, monitor and authorize train move- ments, and is capable of two way communications with train crews of both the passenger and freight equipment, and all MOW and MOE crews who access the shared ROW. • Confirm the transfer of operational authority for a former active freight line to a new passenger operating authority, along with the assumption of responsibility for Command and Control of both freight and passenger traffic. Transportation staff responsible for drafting rules and procedures should recognize that: 1. Since each shared-track operation and its associated communications network will be unique, the approach to Command and Control will have to be specifically tailored for the system. Commencement of any proposed shared-track operation will generate the need for new rules augmented and integrated with appropriate technology. A good foundation for new rules is the freight operators Book of Rules. 2. Shared-track creates the possibility for multiple operating environments within the same cor- ridor, including mainline railroad running, street running, mixing with automotive traffic, Enabling Shared-Track: Technology, Command, and Control 41

pedestrians, traffic signals, line-of-sight operation and other situations. This may be more challenging for a vehicle operator than an exclusive commuter rail operation, and must be addressed in training and the rulebook. A table of contents for a typical rulebook is shown in Appendix 5 “Sample Operating Rulebook Table of Contents.” Technology: Rail Vehicles for Shared-Track Applications Introduction This section describes vehicles and characteristics that can support progress towards the goal of commingled operations. New vehicle designs exhibit improvements in safety and crashworthiness. Energy absorbing design is quickly becoming a standard feature on new light-weight passenger rail vehicles, especially those designed for higher speed operation. While these rail cars do not meet all of the structural and other requirements of 49 CFR Part 238 (commonly referred to as FRA compliance), they can effectively dissipate much of the collision energy that would be gener- ated if the vehicle were to impact a similar vehicle or a car, truck or other object fouling the ROW. Full structural compliance with 49 CFR Part 238 would significantly increase the weight and restrict potential applications of these vehicles. Added weight also affects operating costs, thereby influencing the economic viability of such equipment. Background Freight operations have seen many changes since the 1960s. Freight locomotives and freight cars have grown in size and weight. Freight trains have increased in length. Passenger cars that do not meet federal crashworthiness standards are no longer operated in mixed traffic with today’s freight trains unless specifically grandfathered or otherwise exempted. Before the 1990s, FRA had very few regulations applicable to passenger equipment. The only requirements for pas- senger vehicles were for self-propelled equipment (termed MU locomotives), which required a buff strength of 800,000 lbs for trains over 600,000 lbs in weight, plus various anti-override requirements. The Association of American Railroads (AAR) promulgated equivalent standards for unpowered passenger cars. In the early 1990s, federal concerns about rail passenger safety increased, and passenger safety standards for conventional rail service were upgraded. Interest in and questions concerning the application of European high speed trains in the United States, a more activist attitude to safety regulation, the development of new structural safety technologies (especially crushable, energy absorbing structures), and Amtrak’s push to acquire high speed trains for the Northeast Corri- dor contributed to the change in regulation. After much research and industry discussion, the initial version of Passenger Car Safety Standards (49 CFR Part 238) was finalized and published in 1999. There have been and continue to be periodic revisions to them. New standards required 800,000 lbs buff strength, with no exceptions. Shared-track advocates played no part in the development of the standards; the focus was primarily on intercity and commuter rail equipment. At the time, temporary waivers were granted. Several robust rolling stock designs at the margin of compliance, such as the Budd RDC, were grandfathered. Just as Part 238 was being finalized, shared-track proposals were being developed, notably for the NJ Transit River LINE. Thus the FRA was put in the position of either granting significant excep- tions to its new standards, or rigidly applying the standards and outlawing preexisting, concur- rent shared-track operations in San Diego. One result of these converging events was the 1999 FRA/FTA joint policy statement (now codified in 49 CFR Parts 209 and 211). That policy estab- 42 Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner’s Guide

lished a temporal separation requirement for light rail equipment that operates in a shared-track environment because it lacks the required buff strength. The FRA did contemplate the possibil- ity of commingled operation under some form of fail-safe train separation and an affirmative risk analysis. However, no potential operator has fully undertaken the heavy burden of trying to meet this requirement. Recent studies have acknowledged that temporal separation would be the guiding principle for shared-track because any other service would require some form of waiver from certain FRA regulations, given that existing regulations do not allow latitude to dispense with FRA compli- ance. Nevertheless, the state-of-the-art in these vehicles provides a variety of improvements that may make it easier to prove equivalent safety to the FRA, or at least near-compliance, especially when the vehicle safety features are augmented with other wayside systems and train control technology that contribute to overall safety. Review of Suitable Candidate Rail Vehicles While many vehicles and propulsion systems can serve this potential market, it is most likely that a selected vehicle will be equipped with a diesel engine prime mover whose propulsion sys- tem is either electric or hydraulic. Diesel as the choice of primary power source is fundamentally driven by system cost issues, since diesel eliminates the expense of electrification and also offers greater route and service flexibility. And a conventional roadway or marine diesel engine that fulfills current EPA regulations can be used. Moreover, a diesel prime mover avoids potential electrical clearance limitations to freight traffic and associated signal system complexities. Many common terms of reference [such as diesel multiple units (DMU), light rail vehicles (LRV), electrical multiple units (EMU)] can be confusing or unclear to both experts and non- specialists. For report purposes the term “light passenger rail cars” is suggested as a generic refer- ence to all vehicles in service on, or considered for, shared-track operations that do not comply with FRA structural requirements (49 CFR Part 238). Where a specific reference (DMU, LRV, or EMU) is employed, it is used to focus the discussion on a particular subset of the universe of non- compliant vehicles under consideration. Appendix 7 is a “mini-catalogue” of typical light passen- ger rail vehicles, although some are more suited to shared-track than others. 1) Light Rail Vehicles LRVs suitable for the shared-track environment have evolved from vehicles typically used as streetcars. Such LRVs are currently in operation in a number of U.S. cities, such as San Francisco, Boston, and Philadelphia. LRVs constructed for shared-track do, however, differ from LRVs designed for operation in urbanized areas, in a number of ways. The shared-track LRVs tend to be longer, wider, and heavier than the vehicles designed strictly for operations in urbanized areas, and they operate at higher speeds. However, one of the recent main differences between standard street running LRVs and those intended for shared-track is the variety of propulsion methods, physical dimensions, and capability to enable these vehicles to operate on two or more different rail lines, including a downtown or street run- ning portion. 2) Diesel Multiple Units and Electrical Multiple Units DMUs and EMUs have been used traditionally to operate as commuter and intercity trains on lines with low ridership or those that require a high frequency of service. Those vehicles are con- structed much like standard railway coaches with the addition of a propulsion system and an operator’s cab. A new generation of lighter DMUs and EMUs (jointly referred to as light passen- ger rail cars) has been designed with the shared-track market in mind. They resemble current Enabling Shared-Track: Technology, Command, and Control 43

LRV designs and feature multiple articulated carbody sections, and partial or full low floor design. While some of these new vehicles were designed mainly for railroad operation, several smaller models have been conceived to allow city street operation. Like the LRV, the light passenger rail car offers several different modes of propulsion. Features Preferred for Shared-Track Operations Certain key systems and capabilities exert an overriding influence on vehicle performance and suitability for shared-track duty. Other subsystems such as heating, ventilations, air condition- ing (HVAC), doors, lighting and interiors, are common to nearly all rail cars and have little influ- ence on shared-track. 1) FRA Compliance The main focus of the requirements for vehicle crashworthiness specified in 49 CFR Part 238 is to protect the integrity of the vehicle structure in the event of a collision with another rail vehi- cle. While these requirements make FRA-compliant car bodies more resistant to collision forces, the vehicles are also relatively heavy, and the design flexibility to adapt the vehicle for differing service applications and operating environments is more limited. This is exemplified by the range in weight per seat of North American DMU products. Research showed that FRA-compliant DMUs are 63% heavier on a per seat basis than noncompliant ones, and approximately 25% of the vehicle weight is structure. Part 238 also addresses equipment and interior attachments, elec- trical safety, fuel storage, emergency lighting, and other matters. Other requirements are set out in 49 CFR Part 221 (Rear End Marking Devices), 49 CFR Part 223 (Safety Glazing Standards) and 49 CFR Part 229 (Locomotive Safety Standards). They estab- lish lighting conspicuity and other vehicle requirements. Since deviations will be scrutinized by the FRA, they should be limited to significant components or structural elements where feasibil- ity, cost, or performance is negatively impacted. Noncompliance will have to be explained, and justified from a safety perspective. 2) Crash Energy Management (CEM) While an FRA-compliant rigid car body can withstand a high impact force, if it has no means to absorb and dissipate collision energy, the impact on the occupants will be higher. Crash energy absorbing devices can provide a measure of protection to the train and most importantly to the passengers because the equipment is designed to control the rate, location, and extent of gross car body crush and thereby lower the deceleration forces experienced by the train occupants dur- ing a collision. This CEM approach has been exhibited recently by FRA demonstrations at Pueblo, CO, and also by the Safetrain project in Europe. The benefits of CEM can be envisioned by comparing falling on an ice rink to the experience of falling on grass. Energy absorbing devices serve better than a FRA-compliant rigid structure to cushion the passengers inside the train from bearing the full impact force of a collision. This phenomenon has been noted in a number of National Transportation Safety Board (NTSB) Railroad Accident Reports. Another method of protecting commuters is to provide a large volume unoccupied by riders as a sacrificial zone in the rail car, or multiple strategically placed voids to absorb crash energy. A disadvantage of this approach is that it impacts car capacity. The majority of carbuilders now incorporate some sort of crash energy management features (as shown in Figure 4) on their multiple unit (MU), and LRV vehicles, aimed at mitigating hazards to train crew and passengers in the event of a collision. These devices fall into three primary categories. Each device is designed to absorb incrementally higher impact force loads, 44 Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner’s Guide

ranging from low energy impacts for the hydraulic devices, through moderate, to high impact forces, which will be borne by the vehicle structure. • Hydraulic devices. Operate using hydraulic fluid as a means of absorbing impact force and are already in widespread use in the United States on many LRV and rapid transit vehicles. Low speed impact forces (at speeds up to approximately 5 mph) can be absorbed (Zone A). • Energy absorbing elements. Typically consist of volumes filled with honeycomb type material that absorbs impact energy by deforming during impact at moderate speeds (usually 15–20 mph). Since many of today’s vehicles are built with streamlined end caps, the volume present between the end cab structure and the front end of the car nose allows for considerable impact energy absorption and provides a small crush zone. In the event of deformation, the damaged elements will require replacement, but they are sacrificial components and afford more protection to occupants and vital components of the vehicle (Zones B & C). • Deformable car structure. A design feature of European vehicles, these have end frames designed to collapse in a controlled manner and absorb any force left over after the hydraulic and crush- able devices have been exhausted. The collapsible frame members typically come into play only during higher speed collisions (above 15–20 mph), and are designed to protect the driver’s cab and passenger compartment in the event of a collision. Such an impact will of course result in more extensive damage and generate the need for substantial repairs, but the objective is to offer a higher level of protection to the passengers and crew, and to limit the propagation of the collision effects beyond the crush zone (Zones D & E). 3) Propulsion System DMU vehicles are powered by a diesel engine and come in three basic propulsion configu- rations: diesel-hydraulic, diesel-mechanical and diesel-electric, sometimes also referred to as a DEMU vehicle. Diesel-hydraulic vehicles use a hydraulic transfer case to power the train axles directly from the propulsion engine and diesel-mechanical use a mechanical transfer case, although currently the hydraulic transmission is the preferred of the two. Examples of these types of vehicles include the Colorado Railcar DMU and the Siemens Desiro DMU. Diesel-electric sys- tems, however, first use a diesel driven generator to produce electrical power and then use this elec- trical power to run electrical motors to power the vehicle (similar to a conventional locomotive). The Stadler GTW, Bombardier AGC, and Voyager all use Diesel-Electric propulsion. Diesel-hydraulic propulsion equipment generally costs less, requires less space, and is easier to maintain than diesel-electric. A diesel-powered car with an electric or hydraulic propulsion system will be the most probable system. This vehicle class is likely to accelerate far more quickly than a conventional locomotive hauled commuter rail train, a distinct benefit where track capacity is constrained. Enabling Shared-Track: Technology, Command, and Control 45 Figure 4. Crash energy management (typical con- trolled collapse under increased load).

4) Superior Car Braking Performance As mentioned above, and depending on material, construction techniques, and other struc- tural requirements, light passenger rail cars (defined as non-FRA-compliant DMUs and EMUs) tend to be considerably lighter than rolling stock that complies with FRA buff strength require- ments. Most are equipped with three types of braking systems; friction (either disc or tread or both), dynamic braking (this also can provide regenerative capabilities), and track brakes. Brakes can be actuated by air, hydraulic fluid, spring, or magnetic energy. Because light passenger rail car vehicles weigh less, their stopping performance using only disc brakes can be considerably better than that of an FRA-compliant design. But many modern light passenger rail cars also are equipped with additional track braking systems that provide increased stopping force in emergency situations and are much more resistant to reduced rail adhesion. The deceleration performance of track brakes can exceed 5 MPHPS and can stop a rail car going 30 MPH in approximately 130 feet (e.g., the Stadler GTW 2/6 vehicle). Track brakes are normally activated at relatively low speeds. However, because they are so effective the deceleration rate can be hazardous to passengers, and use should be limited to emergencies or on cars moving at very low speeds. Other operational benefits for shared use accrue from improved braking: A) Redundancy. A relatively high deceleration rate can be maintained in the event of failure of a single brake or system, compared with a conventional commuter rail vehicle. Furthermore the track brakes are a robust and extremely reliable fail-safe design that provides significantly increased braking force. B) Improved signal design. Traditional signal system design parameters incorporate safety fac- tors for loss of braking efficiency. The dependably high deceleration rate and overall system reliability found on these LRV vehicles may offer engineers more design latitude to design a train control system more suitable for passenger service, when compared to traditional rail vehicles. 5) Other Considerations A number of other vehicle-related factors need to be addressed in a shared operation. • Coupler height disparity between FRA-compliant equipment and typical light passenger rail cars. Because of the relative difference in heights of buffing components at the end of each type of vehicle, the potential for vehicle override is increased, thus defeating the buffing mecha- nisms. This disparity argues strongly for fail-safe train control. Some light passenger rail cars can move their couplers to a safer position to protect pedestrians, but this is not possible with typical railroad couplers. • Rail/wheel profile, which affects durability, noise, tendency to derail, and maintenance costs. The AAR wheel profile is standard for all rolling stock operated on the nation’s general sys- tem of rail transportation. It is vital that any light rail vehicle introduced into a shared track operation conform to the AAR wheel profile. • Shunting enhancement devices produce a magnetic field beneath the car that effectively acts as a shunt between the two rails to produce a block occupancy signal independent of any track or wheel conditions associated with standard rail shunting. • Grade crossing collisions are a major concern for rail operations where grade crossings are present. Consequently warning system technology and mitigation techniques properly receive emphasis regardless of the type of rolling stock traversing the rail corridor. Reduced buff strength of light passenger rail cars may affect their survivability in a crash with a large high- way vehicle (truck or bus). However, their high deceleration rate offers a greater possibility of avoiding the collision in the first place or reducing impact speeds; and the energy absorbing features will mitigate collision impact with a large vehicle. Their length and higher acceleration 46 Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner’s Guide

reduces time spent blocking a highway crossing, which reduces driver impatience. To reiterate, the incidence and risk of a grade crossing collision is independent of shared-track operations, and is a hazard for all rail movements at a grade crossing. • EPA emissions compliance is met by most new diesel propulsion units configured to conform to the latest EPA emission requirements. Vehicle Cost Drivers In any system, vehicles are a significant capital cost element and a major operating and maintenance expense throughout their life cycle. Research indicates that the car body is the most expensive element (average 28%), and the propulsion system is next (average 22%) in the magnitude of vehicle costs. Regulators tend to prefer more structural mass. The incremental cost of adding more material may not be all that significant based on the proportions above, but adding more weight to the car body negatively impacts propulsion system design and perform- ance, requiring added braking capability and more robust trucks and suspension elements, in addition to increasing operating costs. A table showing vehicle cost drivers by percentage of total cost is in Appendix 6. A vehicle procurement should budget additional funds of approximately 20% of the vehicle hard cost for associated soft costs (for example warranty, field support, training, tools, spare parts). Spare parts and special tools combine for 7% of overall vehicle procurement cost. Standardization of vehicles, components, and manufacture and assembly methods provides an opportunity to effect a noticeable savings and puts downward pressure on these soft costs, as well. Appendix 5 provides tables of the relative average cost contribution of various components, systems and soft costs. Train controls average only 3% of the total cost of the vehicle (the bulk of train control costs resides in infrastructure elements), so for a relatively small expense, adding mass to the vehicle structure may be avoidable. Train control features may be more compatible with the regulatory goal of fail-safe train separation. Not surprisingly, a second significant factor that affects cost is quantity. The unit procurement cost goes down as quantities go up. A recent survey for the Toronto Transit Commission (TTC) lists unit prices of rail passenger vehicles (subway type cars) and compares them to the quantity purchased. • Car orders between 100 to 150 vehicles ranged between $2.2 to $2.5 million per unit • Car orders exceeding 200 vehicles ranged between $1.7 and $2.2 million per unit The same study listed benchmark prices of $2.3 million for new electric multiple unit type vehicles and $2.5 million for new diesel multiple unit vehicles. In contrast, recent acquisitions of shared-track vehicles have cost approximately $4.0 million per vehicle for very small orders. The data reflect acquisitions by different agencies, and varying technical requirements. The lack of a standard light passenger rail car contributes to higher costs. If each system specifies a different car or selects unique systems and components, controlling costs incurred by a single agency becomes more difficult. The result is that an individual agency bears the front-end and startup costs, rather than spreading them out over a larger number of vehicles. Joint procure- ment and piggy-backing orders can address this issue. Vehicles for Shared-Track Applications Full compliance with FRA requirements for passenger equipment is unlikely. However, to off- set their structural limitations, vehicles for shared-track generally have improved braking rates and energy absorption devices and operate at lower speeds than traditional FRA-compliant passenger Enabling Shared-Track: Technology, Command, and Control 47

equipment. These features provide a higher degree of safety for their operations. Their perform- ance and design characteristics provide an advantage at grade crossings (the number one location for accidents on commuter rail lines), not only to avoid many such collisions, but also to reduce hazards that result from collisions. Such factors should be considered in addition to train control systems and operating procedures when approval for shared-track operations is requested. In many cases, one of the DMU types will be the most appropriate vehicle choice, as low floor diesel powered vehicles are more easily adaptable to route changes, extensions, and pilot pro- grams than LRVs that require a wayside power source (e.g., OHC). Ultimately, the vehicle ought to be considered one part of an integrated system of safety that relies on crashworthiness, train control, communications, training, and R&P. The rail car com- ponent of this system should not be burdened unduly to mitigate all hazards. 1) Selecting the Optimal Vehicle Selecting a heavy or light EMU/DMU or LRV (light passenger rail cars) vehicle is primarily based on operating speed and propulsion system assumptions. Additional influences on vehicle selection and design include: • Operating environment (railroad, on-street, grade separated or reserved ROW); • Clearances (primarily width and height); car static and dynamic envelope; • Platform interfaces; • Weight restrictions; • Future flexibility for service changes; and • Wheel tread and flange profile. A suitable vehicle will likely operate across multiple environments in normal service. Where multiple types of right-of-way are used, operating restrictions, weight, turning radii, and clear- ances on any part of the line influence the technical specifications of rail vehicles. 2) Regulatory Approach Currently FRA’s policy considers commingled operations adequate when accompanied by a pos- itive train separation system. The FRA may consider modifying regulations for such applications. For example, future regulations might offset structural strength requirements with collision energy management design. Regulations could be altered further to describe certain key operating and vehicle design characteristics more suitable for shared-track (e.g., specify freight speeds, minimum track centers, lateral clearances, train control system, energy absorbing features, deceleration rates), effectively creating a new tier of vehicles. Defining certain minimum performance characteristics and features would simplify the FRA’s process of evaluating each vehicle and waiver petition. 3) Standardization If a standard light passenger rail car model could use modular components and systems to allow limited unique system modifications (e.g., to the capacity of an HVAC system) and alter- nate suppliers, such a model effectively could reduce capital and maintenance costs for all oper- ating agencies. An economic benefit of standardized vehicle designs is the resulting cost savings. While each rail car is different, this distribution of proportional costs is useful for planning or budgeting purposes. The data also emphasize three other benefits of standardized designs, car bodies, and systems. 1. Regulatory review process is eased because the FRA does not have to initiate a fresh review for each new light passenger rail car waiver petition. Standardization also results in more accumulated service history with a specific vehicle model. Although the latter is a noneco- nomic benefit, it may enhance the appeal of the concept. 48 Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner’s Guide

2. There is a commonality of maintenance practices, training, documentation, and tooling across multiple users similar to the aviation industry. 3. Standardization contributes to lower vendor prices by creating a larger market, a more constant level of production, and potential for competition. Recommended Vehicle Research The FRA considers the structural capabilities of light passenger rail cars to be the primary deficiency with respect to shared-track operations. Additional research and analysis may alle- viate some of their concerns by providing more technical data to support regulatory evaluations and improve project vehicle design decisions. High value topics that merit further investigation include: 1. Typical braking systems used on light passenger rail car equipment are not incorporated into rolling stock otherwise manufactured for use in the nation’s general rail transportation sys- tem. Accordingly, including a detailed explanation of the performance and reliability of track brakes or hydraulically actuated brakes in a waiver petition would enable the FRA to make a more informed decision. These data should include various comparisons of test results with multiple brake systems fully functional and tests with one or more of the systems cut out or malfunctioning. Test results then can be compared to similar data for conventional freight and commuter rail equipment to justify a signal design more appropriate for a shared-track operation. The data could also support a waiver petition for relief from provisions of 49 CFR Part 236 and contribute to the safety case. 2. Support/encourage computer simulation of structural failures caused by various accident and impact scenarios. Even better would be results of a real-world test between a light pas- senger rail car and a freight car or locomotive. Presently this has been performed for conven- tional freight and commuter rail equipment and is contributing to improved CEM designs for passenger rail cars. There is a need for a similar exercise using light passenger rail cars to verify or improve CEM designs. Such a research program would quantify effects of low and high-speed impacts on the car body and interior, and identify the secondary collision effects on passengers. Com- puter analysis and test results would help validate a risk assessment and support a safety case. Applying Technology to Shared-Track Operations— A Brief Guide Transportation planners and specialists should be familiar with train control systems and appreciate their impacts on safety, operations (both freight and passenger), and capital and oper- ating costs. These systems are a significant contributor to a favorable outcome of an FRA Waiver Petition process and thus affect project viability. Local officials and transit agencies that consider a shared-track project are advised to give the selection of a train control system top priority. 1. Command and Control (C&C) encompasses the train control system, communications net- work, and R&P. C&C provides and enforces movement authority for all rail traffic and is intended to emphasize safety via collision avoidance rather than depending upon vehicle crashworthiness. The system capabilities, relative costs, and performance features help to drive the choices of technology. These selections have a pervasive impact on: • Risk assessment and by extension the waiver petition; • Costs—capital, operations, and maintenance; and • Operational capabilities and limitations of both the freight and passenger services. Enabling Shared-Track: Technology, Command, and Control 49

2. A range of technology from conventional through advanced systems can be considered, and risk reduction is available from both traditional and leading edge technology. Appendix 4 provides relative cost comparisons of various train control systems for planning purposes. 3. Effective and reliable communication between freight carriers and passenger operators is relatively easily provided using conventional technology, without incurring excessive or disproportionate costs. 4. Despite the C&C safety features, the FRA also will scrutinize the vehicle data for crash- worthiness capabilities and other regulatory features. Near compliance to the extent possible should include: • Structural elements and features that manage crash energy and afford some protection for passengers in the secondary collision (passengers impacting elements of the car interior) that would follow an impact; • Lights and markers that look like a rail vehicle to highway vehicle operators at grade crossings; • Window glazing on passenger railcars (both forward ends of bidirectional railcars, side windows). Control of movement authority is the key to safety and regulatory compliance. C&C and vehi- cle choices can enhance the safety case, which in turn is presented in the FRA waiver petition. 50 Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner’s Guide

Next: Chapter 4 - Shared-Track: A Handbook of Examples and Applications »
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TRB’s Transit Cooperative Research Program (TCRP) Report 130: Shared Use of Railroad Infrastructure with Noncompliant Public Transit Rail Vehicles: A Practitioner’s Guide examines a business case for the shared use of non-Federal Railroad Administration-compliant public transit rail vehicles (e.g., light rail vehicles) with freight operations and highlights a business model for such shared-use operations. The report also explores potential advantages and disadvantages of shared-use operations and the issues and barriers that can arise in the course of implementation.

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